cell membranes

Question 1

phospholipid bilayer

Answer 1

double layered phospholipid molecule, hydrophobic fatty acid tails and hydrophilic phosphate heads

Question 2

how thick is the phospholipid bilayer

Answer 2

7nm

Question 3

what molecules can pass through the cell membrane (generally and 5 examples)

Answer 3

generally: lipid soluble molecules, non-polar molecules or very small molecules
examples: vitamin A, H2O, O2, CO2, lipids

Question 4

what are extrinsic proteins

Answer 4

found on the outer surface of the plasma membrane (hydrophilic)

Question 5

what are intrinsic proteins

Answer 5

held within the plasma membrane (hydrohphobic) – span the bilayer

Question 6

definition of osmosis

Answer 6

net movement of water molecules from an area of high water potential to an area of lower water potential down a water potential gradient

Question 7

what are channel proteins

Answer 7

temporary hydrophilic proteins that spans the membrane (very small ions and water soluble molecules can pass through)

Question 8

what method of transport do channel proteins use

Answer 8

diffusion

Question 9

what are carrier proteins

Answer 9

capable of transporting an ion/molecule by active transport (ATP needed when moving against a concentration gradient)

Question 10

what method of transport do carrier proteins do

Answer 10

active transport (and diffusion)

Question 11

whats a glycoprotein

Answer 11

molecule formed when carbohydrate linked to a protein

Question 12

whats a glycolipid

Answer 12

molecule formed when carbohydrate linked to a lipid

Question 13

whats the carbohydrate layer around the membrane called

Answer 13

glycocalyx (glycoprotein and glycolipid)

Question 14

what do high levels of cholesterol do to the membrane

Answer 14

increase fluidity

Question 15

name 3 functions of extrinsic proteins

Answer 15

form recognition sites (by identifying cells), form receptor sites for the hormone attached, provide structural support

Question 16

name 1 function of intrinsic proteins

Answer 16

provide structural support

Question 17

how do carrier proteins change the shape of a molecule

Answer 17

a particular molecule will attach to a protein at a binding site, causes protein to change shape, releases the molecule through the membrane

Question 18

give 3 functions of glycolipids/proteins

Answer 18

cell to cell communication, recognition and hormone reception

Question 19

name 3 types of passive transport

Answer 19

osmosis, diffusion, facilitated diffusion

Question 20

what does facilitated diffusion use (2 things)

Answer 20

carrier proteins and channel proteins

Question 21

name 1 type of active transport and how its used

Answer 21

via carrier proteins, bulk transport

Question 22

what does endocytosis mean

Answer 22

movement of things INTO the cell

Question 23

what does exocytosis mean

Answer 23

movement of things OUT of the cell

Question 24

what does pinocytosis refer to

Answer 24

liquids

Question 25

what does phagocytosis refer to

Answer 25

solids

Question 26

factors affecting diffusion (7)

Answer 26

temperature, concentration gradient, surface area, thickness of membrane, diffusion distance, size of molecule, lipid solubility

Question 27

why does temperature change the rate of diffusion

Answer 27

increased temperature increases kinetic energy and the rate of diffusion (increased random movement)

Question 28

why does concentration gradient change the rate of diffusion

Answer 28

increased concentration gradient = faster rate of diffusion

Question 29

why does surface area change the rate of diffusion

Answer 29

greater surface area = greater rate of diffusion

Question 30

why does diffusion distance change the rate of diffusion

Answer 30

shorter distance = faster rate of diffusion

Question 31

why does the size of molecule change the rate of diffusion

Answer 31

smaller molecules diffuse more quickly than larger

Question 32

why does the lipid solubility change the rate of diffusion

Answer 32

more lipid soluble = faster rate of diffusion

Question 33

equation for the rate of diffusion

Answer 33

(surface area x difference in concentration) / length of diffusion path

Question 34

definition of facilitated diffusion

Answer 34

passive transport of molecules / ions down a concentration gradient across a membrane by protein carrier molecules in membrane

Question 35

what is co-transport

Answer 35

type of facilitated diffusion - brings molecules into cells on same transport molecule / transport 2 substances in the same direction

Question 36

give an example of co-transport

Answer 36

sodium-glucose co-transport

Question 37

does the cell or solution have a higher water potential in a hypotonic solution

Answer 37

the solution

Question 38

does the cell or solution have a higher water potential in a hypertonic solution

Answer 38

the cell

Question 39

how would we describe a plant cell in a hypotonic solution

Answer 39

water would move into the cell by osmosis, the plant cell would become turgid

Question 40

how would we describe an animal cell in a hypotonic solution

Answer 40

water would move into the cell by osmosis, the animal cell would lyse and burst

Question 41

how would we describe a plant cell in a hypertonic solution

Answer 41

water would move out of the cell by osmosis, the plant cell would become plasmolysed

Question 42

how would we describe an animal cell in a hypertonic solution

Answer 42

water would move out of the cell by osmosis, the animal cell would crenate

Question 43

what do we call it when there is no net movement between cell and solution

Answer 43

isotonic -- incipient plasmolysis

Question 44

equation of water potential in hypertonic solution (plant cells)

Answer 44

water potential=solute potential (pressure potential is 0 as the cell membrane and cytoplasm have pulled away from the cell wall)

Question 45

equation of water potential in hypotonic solution (plant cells)

Answer 45

water potential=0 as no more water can move in -- therefore pressure potential=solute potential

Question 46

equation of water potential in isotonic solution -- incipient plasmolysis (plant cells)

Answer 46

pressure potential=0 -- water potential=solute potential

Question 47

what solution is pressure potential present

Answer 47

hypotonic (water moving in)

Question 48

give the three steps of exocytosis

Answer 48

lysosome fuses with the vesicle formed, digestive enzymes digest the solid material, products are absorbed by the cytoplasm